1. Field of the Invention
The invention is directed to a power semiconductor module in pressure-contact form for placement on a cooling component.
2. Description of the Related Art
Known power semiconductor modules such as disclosed in German Published. Application no. DE 197 19 703 A1 comprise a housing having at least one electrically insulating substrate arranged therein, preferably for direct assembly on a cooling component. The substrate comprises an insulator body having a plurality of metal interconnects thereon, which interconnects are insulated from one another, and also power semiconductor components thereon which are circuit connected to these interconnects in circuit-compliant fashion. In addition, known power semiconductor modules have connections for external load and auxiliary connections and connects arranged in the interior thereof. These connections for circuit-compliant connections in the interior of the power semiconductor module are usually in the form of wire bonding connections.
Similarly known are power semiconductor modules with pressure contact, as are known from U.S. Pat. No. 5,438,479 and German Published Application No. DE 199 03 875 A1 or German Patent No. DE 101 27 947 C1. In the case of the first document mentioned, the pressure device has a stable, preferably metal, pressure element for pressure setup, an elastic cushion for pressure storage and a bridge for introducing pressure to separate regions of the substrate surface. The bridge is preferably in the form of a molded plastic body with an area which faces the cushion and from which a multiplicity of pressure fingers extend in the direction of the substrate surface.
A pressure device of this kind pushes the substrate onto a cooling component and hence reliably produces permanent heat transfer between the substrate and the cooling component. In this case, the elastic cushion maintains constant pressure conditions under different thermal loads and over the entire life cycle of the power semiconductor module.
DE 199 03 875 A1 develops the known pressure element such that it firstly has a particularly advantageous ratio of weight and stability and secondly has electrically insulated bushings. To this end, the pressure element is formed as a molded plastic body with an internal metal core. This metal core has recesses to permit connection elements to pass therethrough, preferably auxiliary connection elements in spring contact form. The plastic body surrounds these recesses such that the auxiliary connection elements are electrically insulated from the metal core by the plastic body.
Further pressure elements are also known which have a multiplicity of pressure fingers on their surface facing the substrate. Preferably, the metal core in this context also has a preset sag. In the combination of both measures, a pressure element of this kind can provide the entire functionality of a pressure device as stated above.
German Patent No. DE 101 57 947 C1 discloses a power semiconductor module, in which the load connection elements are in a form such that sections thereof run very close to one another at right angles to the substrate surface and they have inner contact devices, contact feet, extending therefrom which make the electrical contact with the interconnects and simultaneously exert pressure on the substrate and hence make the thermal contact between the latter and a cooling component. In this case, the pressure is introduced by known means.